Math, asked by ArpitaNayak1, 1 year ago

please do no 10 and 11

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Answered by catheld1

2x+y=23
2x=23-y
x=23-y/2
substitute in 2nd equation

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geetsharu1234: we can do it by elimination method also it is more easier than subsititution

geetsharu1234: 2x+y=23

ArpitaNayak1: but the question says to do in eleminaton method

geetsharu1234: answers are of x-3y=-20and 5y-2x=31

geetsharu1234: 2x+y=23

geetsharu1234: 4x-y=19

geetsharu1234: y y will cancel

geetsharu1234: 6x=42,> x=7,> y=23-2x,> put the vale of x to find the value of y=9

geetsharu1234: now put both the value in the given que, x-3y=-20

geetsharu1234: 5y-2x=31

Answered by KVaishu

10. Given two equations, 2x + y = 23 and 4x - y = 19.
Let's add the two equations to eliminate y value.
2x + y = 23
+ 4x - y = 19
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6x = 42
x = 7
Now let's substitute x value in the first equation. We get,
2(7) + y = 23
y = 23 - 14
  y = 9
Hence, x = 7 ; y = 9.
Now let's substitute these values in the second part of the question with equations x - 3y and 5y - 2x.
Substitution in 3rd equation = x - 3y = 7 - 3 ( 9 ) = 7 - 27 = -20
Substitution in 4th equation = 5y - 2x = 5 ( 9 ) - 2 ( 7 ) = 45 - 14 = 31

11. Given expression = ax + by
When x = 2 ; y = 1 then,
a ( 2 ) + b ( 1 ) = 7
⇒ 2a + b = 7 -- Equation 1
When x = -1 ; y = 1 then,
a ( -1 ) + b ( 1 ) = 1
  ⇒ -a + b = 1 -- Equation 2
Now let's subtract equation 2 from equation 1
2a + b = 7
    - -a + b = 1
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3a = 6
a = 2
Now substitute a value in any of the derived equations
2a + b = 7 ⇒ 2 ( 2 ) + b = 7
⇒ 4 + b = 7
  ⇒ b = 3
∴ a = 2 ; b = 3

Hope my answer helps you..

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